Pump for concrete and the like



May 25, 1943'. J. H. FITZGERALD 2,319,981

PUMP FOR CONCRETE AND THE LIKE Filed Dec. 5, 1941 2 sheets-sheet. 1.

May 25, 1943.

.J..H, FITZGERALD PUMP FOR CONCRETE AND THE LIKE 2 sheets-'sheet 2 FiledDec. s, 1941 "IIIIIA IIIIIIIIIIIIIII l JNVENTOR. JAMES H. F1 TZGERALDATToRN'Ey.

Patented May 25, 1943 UNITED STATES vPATENT OFFICE PUMP FOR CONCRETE'ANDTHE LIKEl James H. Fitzgerald, Westfield, N. J.

Application December 3, 1941, Serial No. 421,462

(Cl. 10S-153) Claims.

vof a pumping device by which they are propelled through conduits to theplace of delivery but Ymay be employed for other purposes to which it isadaptable. Its object is to improve the pumping apparatus heretoforeused and shown in various patents and other publications in the art andto provide a pumping and conveying apparatus which will be ,simpler inconstruction, more elicient. and durable and will require a minimum ofrepairs, renewals, operating cost, upkeep and servicing. Y

Heretofore it has been the practice to employ pumps of this class inywhich the feeding hopper outlet andthe outlet of the pressure cylinderare provided with valves synchronized with the piston or plunger, theformer closing and the latter opening onthe forward or power stroke andthe latter closing and the former opening on the return or back strokeof said plunger, so that concrete is fed to the cylinder from the hopperand concretein the discharge or conveying conduit is` prevented frommoving back into the said cylinder on the back stroke and on the forwardstroke the concrete is shut oi from the hopper while the discharge isopened. It has also been the practice to have the forward stroke of theplunger terminate short of the hopper outlet so that the mass ofconcrete in the cylinderrbelow the hopper is never cut off and theplunger always acts directly on that mass and the mass always obstructsthe hopper outlet and must be forced to flow backward toward theplungerto admit more from the hopper flowing by gravity therefrom. Thisconstruction and operation is attended with diiiiculties anddisadvantages and requires the attention of trained operators, thecareful synchronization of the valves and valve operating connectionsand frequent servicing and repairs. It also leads to unsatisfactoryoperation and requires the use of very high pressures which necessitatestrong, heavy construction and cause breaks and undue wear and tear onthe apparatus.

With the present invention, the plunger is so arranged and is given sucha stroke that it passes the hopper outlet, forces the concrete in thecylinder well beyond it and on its return stroke leave a void in thecylinder below the hopper outlet inte which the concrete may freely passtherefrom. It also packs the concrete in the discharge end of thecylinder so that it will not readily iiow backward thereinto and leavesa space between each section or slug of concrete which has been forcedby the plunger to said discharge end and the concrete gravitating intothe cylinder from the hopper in which space a gate may operate freelyand which provides a cushion on the forward stroke of the plunger whichwill absorb the initial pressure created thereby, until the said hopperoutlet is closed off, thereby insuring against the return of air and`liquid in the concrete by pressure to and through the concrete in thehopper. It also involves the use of a cutting edge projecting from thehead of the plunger and passing over the outlet of the hopper in advancethereof which shears the concrete at said mouth and closes the outletbefore suiiicient pressure is built up to cause blowing 'back of saiduid elements on the power stroke of the plunger, as well. as preventingsuch action on the backward stroke until 'another void has been formedbetween the discharge and the feed, and the pressure lieved.

It is believed that in the presentl apparatus on the forward or powerstroke of the-piston the air of the void in the cylinder or pressurechamber between the newly discharged slug or sub-mass of concretetherein adjacent the discharge mouth of the hopper and the column ofconcrete beginning at the discharge 'end of said pressure chamber, beingmany times more fluent than any of the elements of the concrete mixture,seeks to escape from the pressure and spreads in both directions,Penetrating the concrete and between the concrete and the cylinder untilit impinges against the cylinder head, where it accumulates, thustending to clear the path of the piston and lubricate between it and thecylinder and greatly reducing friction and wear on these parts. It isalso believed that on the return stroke of the piston this air beingunder thus recompression maintains pressure on the column of concreteinthe cylinder end and conveying conduit so as to prevent the saidcolumn from retreating under the influence of Suction and thus cause itto pack or jam and prevent a back'- ward flow. This second action' ofthe trapped air of the void renders the use 'of a gate between thevpiston and the' column of concrete unnecessary in most cases. With orwithout the gate, however, a bend in the cylinder end or nearby conduitmay be employed to promote this packing or jamming of the concrete.However, whether this theory of operation is correct or not, thecreation and maintenance of the void performs a useful and importantfunction in promoting the action stated. It is believed that it l'showninY Fig. 1.

also tends to prevent arching of the concrete in the neck of the hopperabove the discharge opening by momentarily agitating the concretetherein from below when the piston retreats, as it has been found noperation that this arching does not occur, at least to any seriousextent. If desired, however, an agitator in the neck of the hopper maybe employed to prevent packing or arching and insure a free and rapiddischarge. It has also been found that friction and wear on the pistonand 4cylinder are reduced to a degree far below that which usuallyoccurs in pumps of this type, and that the piston works freely and withhigh efficiency.

It will be seen from the foregoing that the invention includes not onlyan apparatus ybut Ya method of operation performed by that apparatuswhich comprises the constant maintenance of a void filled with air whichis compressed and expanded alternately and provides a free space`Various other functions and advantages -will 'be apparent to thosefamiliar with the construcftion and operation of apparatus of this typefrom ythe following description.

The improvements are illustrated in the accompanying drawings, referredto herein, which show .an exemplary embodiment thereof and in which-Fig. 1 is a vertical, longitudinal, medial section partly inY elevation,-of the pumping apparatus, .with-the piston or plunger retracted and thegate closed;

Fig. 2 is a similar-view of the pump with the piston at .the-end ofitsforward strokeand the V,gateeopem Fig. -3 is-a vertical'cross-section ofthe cylinder .andgate housing-on the line 3-3 of Fig. 2 showv.ing thegate lin 'open position;

Fig. 4 is a view similar to Fig. 3 showing the :gate closed; and

Fig. 5 is 'a side elevation of the cylinder, gate .and `gate housing.

The specimen power vunit for operating the Vpump consistsv essentiallyof a motor I with small pulley 2 on its shaft 3, a large pulley 4mounted in bearings-5 by atrunnion shaft 6 and driven Jby"a'belt1,;apinion 8 on shaft 1 meshing with .alargegear wheel v9 having its axisI0, to which ra crankarm II is keyed, xed thereto.

This power unit is suitably -mounted on a` frame consisting of the baseframe member I3 and the rupperffrarnel member I4 bolted thereto, all asThev frame I5 supporting the other parts ofthe apparatus is securely xedto the frame I3. of the power unit and mounts the cylinder I6 on whichthe feed hopper I'I is in turn fixed and supported.

Thelconnecting rod I8 of the piston I9 is operativelyv-connected withthe crank arm II to be ydriven thereby'by the crank pin I2 and bearingVhead. onk the rod. The opposite end of the piston rod is connectedinside the skirt I9' of the piston by-a wrist pin 2l engaged with thepiston bearing 22.

The piston I9 has secured to its head by means of one-or more'fscrewbolts 23 passing therethroughVA and through a'packing disk 24 andAthreads therein, a heavy disk with a semicylindrical YmemberY261projecting forwardly therefrom at .its'fupper half and provided with:a rcutting' Yedge 2l. This member is preferably a separate .piece which`may be removed from the piston headand replaced when worn or damaged,

rounded to reduce friction and wear.

but it may be made integral with the piston if desired. Its primarypurpose is to cut through the concrete at the mouth of the hopper, atthe beginning of the forward stroke of the piston, sever the sub-mass ofconcrete deposited in the cylinder I6 beneath said mouth on thepreceding retraction of the piston and seal olf the mouth opening beforethe pressure built up by said stroke has reached a degree which willcause the air and liquid content of the plastic concrete mixturecommonlycalled soup-to blow up into the hopper to any undesirable extent. Therewill be a slight passage of air under compression, following the path ofleast resistance, between the forward cutting edge of this member andforward edge of the hopper mouth, which will tend to clear the concretefrom these edges and prevent the larger aggregates-usually cracked stoneor gravelfrom being caught between them. This air will be suppliedprincipally from .the concrete void A in the forward portion of thecylinder left by the piston on its backward stroke and pushed forward bythe mass of concrete dumped into the cylinder ahead of the piston beforethe piston starts another forward stroke. The member 26 also permits thepiston to retreat to a point where the air in the void A has anopportunity to expand to a certain extent before the hopper mouth isuncovered, so that it will not at that time blow up into the concretemass C in the hopper except to a limited extent and sufficient only toloosen the packing of said concrete in the neck. The void will then formbehind the retracted piston from beyond the point where the gate islocated to the opposite side of the hopper so that the concretedescending from the hopper will have an unobstructed path, to fill thecross-section of the cylinder and spread laterally.

The cylinder is provided with an internal wear lining 28 preferably intwo sections joined back of the member 25 when at home position so thatthe forward part may easily be removed and replace'd if necessary. Atits forward edge the lining has a flange 29 which is secured between themain support member I5 and the edge of the cylinder, and at the edges ofits opening 28 which surrounds the mouth of the hopper it is Its forwardedge terminates at the place where the forward or power stroke of thepiston and its cutting edge ends, and at this point provides a slightledge reducing the diameter of the cylinder and retarding the slightbackward movement of the column of concrete B in the discharge end ofthe cylinder and the conveying conduit 30 forming a joined continuationthereof.

The gate 3I works in a housing 32 and has a ring at its top to which maybe connected any suitable means for opening it before the pistonadvances and closing it as the piston starts to retreat so that it willact against the backward movement, if any, of the concrete column B. Ithas straight sides and an upwardly `curved bottom so that it does not llthe cross section of the cylinder lbut leaves spaces at sides andbottom, insufficient to permit the concrete to ow therethrough andsufficient to cause i't to pack if necessary and form a jam. Thesespaces or apertures will, however, permit air to pass the gate freely,Any satisfactory mechanism synchronized with the piston, as, forillustration, a spring rod connected with the piston drive and operatinga .cam member or lever for raising and lowering the gate, may beemployed to `operate the gate. The gate operates in a transverse slot inthe cylinder 'and its lining and this slot may be provided with packingto prevent leakage around the gate if necessary.

It will be understood that the length of the piston stroke, the pistonan-d the member 26 may be varied to secure the best results and thatother details of the exemplary embodiment may be changed, also that anysuitable power unit and power transmitting mechanism may be employedwithout departing from the scope of the invention.

'The improvements may be used for pumping the usual wet |and dry plasticmixed concrete, which usually -consists of broken rock or gravel, sand,Portland cement and sufficient water to produce a wet or dry mix, but isnot limited to the pumping of su-ch concrete mixtures as distinguishedfrom other more or less fluent solids in a divided state either dry ormixed with liquid,

What I claim is:

l. A piston or plunger, an elongated cylindrical pressure chamber inwhich the plunger reciprocates, power means for moving said plungerforward to drive the material to be pumped and backward therefrom. afeeding container for said material having -a discharge opening intosaid chamber along the path of said plunger an-d between its forward andbackward positions and adapted to discharge material into said chamberin advance |of the said plungers forward stroke, a projecting memberrigid with t'he forward end of the head Iof said plunger entirely withinthe extreme radial dimensions of the plunger constructed and larrangedto pass said discharge opening in advance of said plunger yand to cutoff discharged material from the body of material in the container `and.close the opening.

2. A pist-on or plunger, an velongated cylindrical pressure chamber inwhich the plunger reciprocates, power means for moving said plungerforward to drive the material to be pumped and backward therefrom, afeeding container for said material having a discharge opening into saidchamber along the path of said plunger and between the forward andbackward positions and adapted to discharge material int-o said chamberin advance yof the said plungers forward stroke, a projecting membercomprising a cylindric piece of metal conforming approximately to theinner contour of the pressure chamber rigid with the forward end of thehead of said plunger and flush with the extreme radial dimensions of theplunger constructed and arranged to pass said discharge opening inadvance of said plunger and to cut off discharged material from the bodyof material in the `container and close the opening.

3. A piston or plunger, an elongated cylindrical pressure chamber inwhich the plunger reciprocates, power means for moving said plungerforward to drive the material to be pumped and backward therefrom, afeeding container for said material having a discharge opening into saidchamber along the path of said plunger and between the forward andbackward positions and adapted to 4discharge material into said chamberin advance of the said plungers forward stroke, a projecting membercomprising a cylindric piece of metal conforming approximately to theinner contour of the pressure chamber and a forward cutting edge thereonrigid with the forward end of the head of said plunger and ush with theextreme radial ldimensions of the plunger constructed and |arranged topass said discharge opening in advance of said plunger and to cut -ofdischarged material from the body of material in the container and closethe opening.

4. A piston or plunger, an elongated cylindrical pressure chamber inwhich the plunger reciprocates, power means for moving said plungerforward to drive the material to be pumped and backward therefrom, afeeding container for said material having a discharge opening into saidchamber along the path `of said plunger and between the forward andbackward positions and 4adapted to discharge material into said chamberin Iadvance of the said plungers forward stroke, a projecting membercomprising a cylindric piece of metal -conforming approximately to theinner contour of the pressure chamber rigid with the forward end of thehead of said plunger and flush with the extreme radial dimensions of theplunger constructed and arranged to pass said discharge opening inadvance of said plunger and to cut off discharged material from the bodyof material in the container and close the opening, and means adjacent avoid for checking backward movement of said compressed concrete.

5. A piston or chamber, an elongated cylindrical pressure chamber inwhich the plunger reciprocates, power means for moving said plungerforward to drive the material to be pumped and backward therefrom, 'afeeding container for said material having a discharge opening into saidchamber along the path of said plunger and between its forward andbackward positions and `adapted ,to discharge material into said chamberin advance of the said plungers forward stroke, a projecting memberrigidly secured to the forward end of the head of said plunger entirelywithin the extreme radial dimensions of the plunger constructed andarranged to pass said discharge opening in advance of said plunger andto cut off discharged material from the body of material in thecontainer and close the opening and to pass said discharge opening afterthe piston of the return stroke of the latter.

JAMES H. FITZGERALD.

